The present invention involves compositions for the dyeing of hair with nitro dyes, whereby new derivatives of 1,4-diamino-5-chloro-2-nitrobenzene are employed, as well as a process for the production of these derivatives and methods for the use thereof.
Nitro dyes have acquired an essential importance in the field of hair coloring. Through combination of various nitro dyes coloring compositions can be prepared which make possible the dyeing of hair into natural and popular, so-called "mod" (i.e. modern) tones, without the addition of oxidation means. The nitro dyes are likewise important components of oxidation hair coloring compositions, since they make it possible in simple manner to produce natural or mod nuances.
Numerous particular requirements are placed on nitro dyes that are employed for the coloring of human hair. Thus they must be non-harmful both from a toxicological and dermatological point of view, and make it possible to obtain colorations of a desired intensity, a prerequisite for which among others is also a sufficient water-solubility. Additionally required for the obtained hair colorations are good light, acid and friction fastness. It is moreover a prerequisite for their employment in oxidation hair dyeing compositions that they remain stable in the presence of hydrogen peroxide in ammoniacal solution.
For some time now, in addition to others, derivatives of o- and p-phenylene-diamine, e.g. the yellow dye 4-nitro-o-phenylenediamine or the red 2-nitro-p-phenylenediamine have been employed as nitro dyes in hair coloring compositions. However, these dyes do not fulfill the above mentioned conditions, in particular the physiological prerequisites, to a satisfactory extent.
5-chloro-2-nitro-p-phenylenediamine derivatives, which better fulfill these prerequisites, are known from DE-PS No. 2 157 844. A disadvantage of the disclosed compounds is their relatively low water-solubility, which hinders employment in higher concentrations for the obtaining of greater deepness of color.